Carmustine impurity A is primarily used in the research and development of pharmaceuticals, particularly in the quality control and analytical testing of Carmustine, a chemotherapeutic agent. It serves as a reference standard to ensure the purity and consistency of Carmustine during its production process. By identifying and quantifying this impurity, manufacturers can maintain compliance with regulatory standards and ensure the safety and efficacy of the final drug product. Additionally, it aids in studying the degradation pathways and stability of Carmustine, which is crucial for optimizing its formulation and storage conditions.